In the case of my roll-off-roof obsy, I have been trying to think of a way to start up everything automatically. I need to park my mount before I move the roof. In the design of my roof controller, I have sensors that prevent the roof moving unless the mount is in a safe position but currently I have no method to prevent a mount slewing into the roof .
Exploring the slave options for start of sequence I had a near disaster last night that by pure luck did not damage anything, missing the rafters by an inch. These are some observations:
a) In the case of a Paramount, when it is parked and powered down, when it powers up, it does not know that it is parked. -> That can mean that if the imaging software uses the park status to kick off roof opening and unpark, this will fail. In the case of a Paramount, it also has to be homed first, before it will slew. So long that auto-home is disabled on ASCOM connection, there is no risk of a collision but the sequence will not start up from ‘cold’. At least for Paramount users, you have to prime the system first and then hibernate it, rather than booting from cold park position. (For remote obsy that are permanently powered, this may be no big deal)
b) Because of a), I pre-prepared the mount, powering it up and homing it with the roof open and then parked it, closed the roof and left all the hardware and software running. In SGP, I got caught out by the ‘slave to telescope’ option resetting itself when I restarted the sequence At the start of sequence, it did not attempt to open the roof and slewed to target, neatly inserting itself between two roof beams.
c) At end of sequence - so long as I remembered to reset the ‘slave to telescope’ option in the control panel, everything went well - since I have fail-safes in the roof controller, the worse outcome is that the mount does not park and the roof stays open.
d) Thinking through this - it looks increasingly unlikely that I can achieve a true automatic startup from cold. Even from a hibernate state, while the ‘slave to telescope’ option self-cancels it is too dangerous to rely upon human nature to set this option each time I start a sequence or reset it each time I restart a sequence.
e) As a consequence of the above, I need to develop an independent fail-safe - preventing the mount slewing into a closed roof. I think the only way I can do this is with my independent Obsy App, which monitors physical roof and mount position sensors. It will need to issue an immediate ABORT to the mount, if the mount park sensor detects movement while the roof is closed.
f) In regard to the self-cancelling ‘slave to telescope’ option - clearly in my case it is a liability - what is the error state with making it stick?